Field of the Invention
The present invention relates to a motor, and more particularly, to a sensing unit of a motor.
Discussion of Related Art
In general, a motor includes a rotating shaft, a rotor that surrounds the rotating shaft, a stator that is spaced a predetermined interval from the rotor, and a housing that fixes the stator.
The rotating shaft may be supported by the housing. The rotor includes a rotor core that surrounds the rotating shaft and a drive magnet that is coupled to the rotor core. The stator includes a plurality of stator cores and coils that are wound around each of the stator cores. When current is applied to the stator, the rotor rotates due to interaction between the stator and the rotor.
The motor may include a sensor and a sensing magnet for detecting the amount of rotation of the motor. The sensing magnet is generally magnetized on an inner race, and includes main poles that are arranged to correspond to those of the drive magnet and frequency generator (FG) poles that are magnetized on an outer race and are arranged more densely than the main poles.
Accordingly, a rotation angle of the motor may be accurately measured, and the motor may be softly driven. However, magnetic flux interference between the main poles and the FG poles may occur, thereby leading to waveform distortion.
Although a dummy track may be disposed between the main poles and the FG poles, there is a limitation on a size of the sensing magnet, and thus it is difficult to secure sufficient space for the dummy track.